FILE - South Korean protesters stage a rally to oppose the plan to deploy the advanced U.S. missile defense system called Terminal High-Altitude Area Defense, or THAAD, near the U.S. Embassy in Seoul, South Korea, April 29, 2017. Bilateral relations between South Korea and China took a significant hit in 2017 after South Korea installed an advanced U.S. missile defense system to counter nuclear and missile threats from North Korea. The decision angered China, which claimed that the anti-missile system in South Korea could be reconfigured to peep into its territory. (AP Photo/Ahn Young-joon, File)